Conduits for transporting fluids and methods of fabricating the same

ABSTRACT

A method of fabricating a conduit comprises steps of attaching a first tubular-outboard-ply end of a tubular outboard ply to a first inner collar portion of a first collar with a third weld and attaching a second tubular-outboard-ply end to a second inner collar portion of a second collar with a fifth weld. The method additionally comprises steps of interconnecting the first inner collar portion and a first outer collar portion of the first collar with a first weld and interconnecting the second inner collar portion and a second outer collar portion of the second collar with a sixth weld. The method also comprises attaching a trimmed first corrugated-inboard-ply end to the first outer collar portion with a second weld, attaching a trimmed second corrugated-inboard-ply end to the second outer collar portion with a fourth weld, and communicatively coupling a first sensor with an interstitial space.

GOVERNMENT LICENSE RIGHTS

This invention was made with Government support under HR0011-17-9-0001awarded by Defense Advanced Research Projects Agency. The government hascertain rights in this invention.

TECHNICAL FIELD

The present disclosure relates to conduits for transporting fluids andmethods of fabricating such conduits.

BACKGROUND

Flexible conduits, used in cryogenic propulsion systems, are susceptibleto manufacturing variances and incidental damage. If not timelyidentified, failure of a flexible conduit, such as apressurized-propellant feed line, could potentially lead to damage ofthe main propulsion system.

SUMMARY

Accordingly, apparatuses and methods, intended to address at least theabove-identified concerns, would find utility.

The following is a non-exhaustive list of examples, which may or may notbe claimed, of the subject matter, disclosed herein.

One example of the subject matter, disclosed herein, relates to aconduit for transporting a fluid. The conduit comprises a first collarthat comprises a first outer collar portion, a first inner collarportion, and a first weld, hermetically coupling the first outer collarportion and the first inner collar portion. The conduit furthercomprises a second collar that comprises a second outer collar portion,a second inner collar portion, and a sixth weld, hermetically couplingthe second outer collar portion and the second inner collar portion. Theconduit also comprises a bellows that comprises a central axis, acorrugated inboard ply, a corrugated outboard ply, and an interstitialspace, located between the corrugated inboard ply and the corrugatedoutboard ply. The corrugated inboard ply is interposed between thecorrugated outboard ply and the central axis. The conduit additionallycomprises a second weld, hermetically coupling the corrugated inboardply and the first outer collar portion. The conduit further comprises athird weld, hermetically coupling the corrugated outboard ply and thefirst inner collar portion. The conduit also comprises a fourth weld,hermetically coupling the corrugated inboard ply and the second outercollar portion. The conduit additionally comprises a fifth weld,hermetically coupling the corrugated outboard ply and the second innercollar portion. The conduit further comprises a first sensor,communicatively coupled with the interstitial space.

The conduit provides a compliant structure for transportation of fluids,such as cryogenic fuels, that accommodates displacements encounteredduring operation. The first sensor, being communicatively coupled withthe interstitial space, allows the first sensor to monitor conditionswithin the interstitial space. In particular, the first sensor enablesdetection of leaks in the corrugated inboard ply by detecting changes inconditions within the interstitial space. The first weld facilitateshermetical coupling of the first outer collar portion and the firstinner collar portion while allowing the first outer collar portion to beseparately formed from and interconnected to the first inner collarportion, which enables the bellows to be hermetically coupled to thefirst collar in a simple and efficient manner. Similarly, the sixth weldfacilitates hermetical coupling of the second outer collar portion andthe second inner collar portion while allowing the second outer collarportion to be separately formed from and interconnected to the secondinner collar portion, which enables the bellows to be hermeticallycoupled to the second collar in a simple and efficient manner. Thesecond weld promotes a strong, reliable, and sealed connection betweenthe corrugated inboard ply and the first outer collar portion. The thirdweld promotes a strong, reliable, and sealed connection between thecorrugated outboard ply and the first inner collar portion. The fourthweld promotes a strong, reliable, and sealed connection between thecorrugated inboard ply and the second outer collar portion. The fifthweld promotes a strong, reliable, and sealed connection between thecorrugated outboard ply and the second inner collar portion.Communicatively coupling the interstitial space with the first sensorallows leaks of fluid or gas into the interstitial space through thecorrugated inboard ply to be detected at a location external to thefirst collar and the second collar.

Another example of the subject matter, disclosed herein, relates to aconduit for transporting a fluid. The conduit comprises a first collarthat comprises a first outer collar portion, a first inner collarportion, and a first weld, hermetically coupling the first outer collarportion and the first inner collar portion. The conduit furthercomprises a bellows that comprises a central axis, a corrugated inboardply, a corrugated outboard ply, and an interstitial space, locatedbetween the corrugated inboard ply and the corrugated outboard ply. Thecorrugated inboard ply is interposed between the corrugated outboard plyand the central axis. The conduit also comprises a second weld,hermetically coupling the corrugated inboard ply and the first outercollar portion. The conduit additionally comprises a third weld,hermetically coupling the corrugated outboard ply and the first innercollar portion. The conduit further comprises a first sensor,communicatively coupled with the interstitial space.

The conduit provides a compliant structure for the transmission offluids, such as cryogenic fuels, that accommodates displacementsencountered during operation. The first sensor, being communicativelycoupled with the interstitial space, allows the first sensor to monitorconditions within the interstitial space. In particular, the firstsensor enables detection of leaks in the corrugated inboard ply bydetecting changes in conditions within the interstitial space. The firstweld facilitates hermetical coupling of the first outer collar portionand the first inner collar portion while allowing the first outer collarportion to be separately formed from and interconnected to the firstinner collar portion, which enables the bellows to be hermeticallycoupled to the first collar in a simple and efficient manner. The secondweld promotes a strong, reliable, and sealed connection between thecorrugated inboard ply and the first outer collar portion. The thirdweld promotes a strong, reliable, and sealed connection between thecorrugated outboard ply and the first inner collar portion.Communicatively coupling the interstitial space with the first sensorallows leaks of fluid or gas into the interstitial space through thecorrugated inboard ply to be detected at a location external to thefirst collar.

Another example of the subject matter, disclosed herein, relates to amethod of fabricating a conduit. The method comprises attaching a firsttubular-outboard-ply end of a tubular outboard ply to a first innercollar portion of a first collar with a third weld. The method furthercomprises attaching a second tubular-outboard-ply end of the tubularoutboard ply, which is opposite the first tubular-outboard-ply end ofthe tubular outboard ply, to a second inner collar portion of a secondcollar with a fifth weld. The method also comprises inserting a tubularinboard ply into the tubular outboard ply and advancing the tubularinboard ply along an interior of the tubular outboard ply until a firsttubular-inboard-ply end of the tubular inboard ply protrudes a firstdistance past the first inner collar portion, and a secondtubular-inboard-ply end protrudes a second distance past the secondinner collar portion. The first distance is greater than a firstpredetermined distance and the second distance is greater than a secondpredetermined distance. The method additionally comprises simultaneouslycorrugating the tubular inboard ply and the tubular outboard ply to forma bellows, having a central axis and comprising a corrugated outboardply, a corrugated inboard ply, and an interstitial space, locatedbetween the corrugated inboard ply and the corrugated outboard ply. Thecorrugated outboard ply is formed from the tubular outboard ply, and thecorrugated inboard ply is formed from the tubular inboard ply. Themethod further comprises trimming a first corrugated-inboard-ply end ofthe corrugated inboard ply, corresponding to the firsttubular-inboard-ply end of the tubular inboard ply, to create a trimmedfirst corrugated-inboard-ply end that protrudes the first predetermineddistance past the first inner collar portion. The method also comprisestrimming a second corrugated-inboard-ply end of the corrugated inboardply, corresponding to the second tubular-inboard-ply end of the tubularinboard ply, to create a trimmed second corrugated-inboard-ply end thatprotrudes the second predetermined distance past the second inner collarportion. The method additionally comprises interconnecting the firstinner collar portion and a first outer collar portion of the firstcollar with a first weld. The method further comprises interconnectingthe second inner collar portion and a second outer collar portion of thesecond collar with a sixth weld. The method also comprises attaching thetrimmed first corrugated-inboard-ply end of the corrugated inboard plyto the first outer collar portion with a second weld. The methodadditionally comprises attaching the trimmed secondcorrugated-inboard-ply end of the corrugated inboard ply to the secondouter collar portion with a fourth weld. The method further comprisescommunicatively coupling a first sensor with the interstitial space.

The method facilitates fabrication of the conduit in an efficient andsimple manner. The conduit provides a compliant structure for thetransmission of fluids, such as cryogenic fuels, that accommodatesdisplacements encountered during operation. Simultaneously corrugatingthe tubular outboard ply and the tubular inboard ply to form the bellowspromotes complementary the corrugations in the corrugated inboard plyand the corrugated outboard ply of the bellows. The first sensor, beingcommunicatively coupled with the interstitial space, allows the firstsensor to monitor conditions within the interstitial space. The firstweld facilitates hermetical coupling of the first outer collar portionand the first inner collar portion while allowing the first outer collarportion to be separately formed from and interconnected to the firstinner collar portion, which enables the bellows to be hermeticallycoupled to the first collar in a simple and efficient manner. Similarly,the sixth weld facilitates hermetical coupling of the second outercollar portion and the second inner collar portion while allowing thesecond outer collar portion to be separately formed from andinterconnected to the second inner collar portion, which enables thebellows to be hermetically coupled to the second collar in a simple andefficient manner. The second weld promotes a strong, reliable, andsealed connection between the corrugated inboard ply and the first outercollar portion. The third weld promotes a strong, reliable, and sealedconnection between the corrugated outboard ply and the first innercollar portion. The fourth weld promotes a strong, reliable, and sealedconnection between corrugated the inboard ply and the second outercollar portion. The fifth weld promotes a strong, reliable, and sealedconnection between the corrugated outboard ply and the second innercollar portion. Advancing the tubular inboard ply along an interior ofthe tubular outboard ply until the first tubular-inboard-ply end of thetubular inboard ply protrudes a first distance past the first innercollar portion, and the second tubular-inboard-ply end protrudes asecond distance past the second inner collar portion accommodates thereduction in the length of the tubular inboard ply after the tubularinboard ply is corrugated. Trimming the first corrugated-inboard-ply endof the corrugated inboard ply and trimming the secondcorrugated-inboard-ply end of the corrugated inboard ply promotesachieving a desired length of the corrugated inboard ply aftercorrugation of the tubular inboard ply. Communicatively coupling theinterstitial space with the first sensor allows leaks of fluid or gasinto interstitial space the through the corrugated inboard ply to bedetected at a location external to the first collar and the secondcollar.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described one or more examples of the present disclosure ingeneral terms, reference will now be made to the accompanying drawings,which are not necessarily drawn to scale, and wherein like referencecharacters designate the same or similar parts throughout the severalviews, and wherein:

FIGS. 1A, 1B, and 1C, collectively, are a block diagram of a conduit fortransporting a fluid, according to one or more examples of the presentdisclosure;

FIG. 2 is a schematic, perspective, sectional view of a first collarportion of the conduit of FIGS. 1A, 1B, and 1C, according to one or moreexamples of the present disclosure;

FIG. 3 is a schematic, perspective, sectional view of the conduit ofFIGS. 1A, 1B, and 1C, according to one or more examples of the presentdisclosure;

FIG. 4 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 5 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 6 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 7 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 8 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 9 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 10 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 11 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIG. 12 is a schematic, perspective, sectional view of a sub-assembly ofthe conduit of FIGS. 1A, 1B, and 1C, according to one or more examplesof the present disclosure;

FIGS. 13A-13E, collectively, are a block diagram of a method offabricating a conduit of FIGS. 1A, 1B, and 1C, according to one or moreexamples of the present disclosure;

FIG. 14 is a block diagram of aircraft production and servicemethodology; and

FIG. 15 is a schematic illustration of an aircraft.

DETAILED DESCRIPTION

In FIGS. 1A, 1B, and 1C, referred to above, solid lines, if any,connecting various elements and/or components may represent mechanical,electrical, fluid, optical, electromagnetic and other couplings and/orcombinations thereof. As used herein, “coupled” means associateddirectly as well as indirectly. For example, a member A may be directlyassociated with a member B, or may be indirectly associated therewith,e.g., via another member C. It will be understood that not allrelationships among the various disclosed elements are necessarilyrepresented. Accordingly, couplings other than those depicted in theblock diagrams may also exist. Dashed lines, if any, connecting blocksdesignating the various elements and/or components represent couplingssimilar in function and purpose to those represented by solid lines;however, couplings represented by the dashed lines may either beselectively provided or may relate to alternative examples of thepresent disclosure. Likewise, elements and/or components, if any,represented with dashed lines, indicate alternative examples of thepresent disclosure. One or more elements shown in solid and/or dashedlines may be omitted from a particular example without departing fromthe scope of the present disclosure. Environmental elements, if any, arerepresented with dotted lines. Virtual (imaginary) elements may also beshown for clarity. Those skilled in the art will appreciate that some ofthe features illustrated in FIGS. 1A, 1B, and 1C may be combined invarious ways without the need to include other features described inFIGS. 1A, 1B, and 1C, other drawing figures, and/or the accompanyingdisclosure, even though such combination or combinations are notexplicitly illustrated herein. Similarly, additional features notlimited to the examples presented, may be combined with some or all ofthe features shown and described herein.

In FIGS. 13A-13E, referred to above, the blocks may represent operationsand/or portions thereof and lines connecting the various blocks do notimply any particular order or dependency of the operations or portionsthereof. Blocks represented by dashed lines indicate alternativeoperations and/or portions thereof. Dashed lines, if any, connecting thevarious blocks represent alternative dependencies of the operations orportions thereof. It will be understood that not all dependencies amongthe various disclosed operations are necessarily represented. FIGS.13A-13E and the accompanying disclosure describing the operations of themethod(s) set forth herein should not be interpreted as necessarilydetermining a sequence in which the operations are to be performed.Rather, although one illustrative order is indicated, it is to beunderstood that the sequence of the operations may be modified whenappropriate. Accordingly, certain operations may be performed in adifferent order or simultaneously. Additionally, those skilled in theart will appreciate that not all operations described need be performed.

In the following description, numerous specific details are set forth toprovide a thorough understanding of the disclosed concepts, which may bepracticed without some or all of these particulars. In other instances,details of known devices and/or processes have been omitted to avoidunnecessarily obscuring the disclosure. While some concepts will bedescribed in conjunction with specific examples, it will be understoodthat these examples are not intended to be limiting.

Unless otherwise indicated, the terms “first,” “second,” etc. are usedherein merely as labels, and are not intended to impose ordinal,positional, or hierarchical requirements on the items to which theseterms refer. Moreover, reference to, e.g., a “second” item does notrequire or preclude the existence of, e.g., a “first” or lower-numbereditem, and/or, e.g., a “third” or higher-numbered item.

Reference herein to “one example” means that one or more feature,structure, or characteristic described in connection with the example isincluded in at least one implementation. The phrase “one example” invarious places in the specification may or may not be referring to thesame example.

As used herein, a system, apparatus, structure, article, element,component, or hardware “configured to” perform a specified function isindeed capable of performing the specified function without anyalteration, rather than merely having potential to perform the specifiedfunction after further modification. In other words, the system,apparatus, structure, article, element, component, or hardware“configured to” perform a specified function is specifically selected,created, implemented, utilized, programmed, and/or designed for thepurpose of performing the specified function. As used herein,“configured to” denotes existing characteristics of a system, apparatus,structure, article, element, component, or hardware which enable thesystem, apparatus, structure, article, element, component, or hardwareto perform the specified function without further modification. Forpurposes of this disclosure, a system, apparatus, structure, article,element, component, or hardware described as being “configured to”perform a particular function may additionally or alternatively bedescribed as being “adapted to” and/or as being “operative to” performthat function.

Illustrative, non-exhaustive examples, which may or may not be claimed,of the subject matter according the present disclosure are providedbelow.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, conduit 100 for transporting a fluid is disclosed. Conduit 100comprises first collar 102 that comprises first outer collar portion104, first inner collar portion 106, and first weld 136, hermeticallycoupling first outer collar portion 104 and first inner collar portion106. Conduit 100 further comprises second collar 103 that comprisessecond outer collar portion 105, second inner collar portion 107, andsixth weld 137, hermetically coupling second outer collar portion 105and second inner collar portion 107. Conduit 100 also comprises bellows108 that comprises central axis 180, corrugated outboard ply 112,corrugated inboard ply 110, interposed between corrugated outboard ply112 and central axis 180, and interstitial space 126, interposed betweencorrugated inboard ply 110 and corrugated outboard ply 112. Conduit 100additionally comprises second weld 138, hermetically coupling corrugatedinboard ply 110 and first outer collar portion 104. Conduit 100 furthercomprises third weld 134, hermetically coupling corrugated outboard ply112 and first inner collar portion 106. Conduit 100 also comprisesfourth weld 186, hermetically coupling corrugated inboard ply 110 andsecond outer collar portion 105. Conduit 100 additionally comprisesfifth weld 184, hermetically coupling corrugated outboard ply 112 andsecond inner collar portion 107. Conduit 100 further comprises firstsensor 116, communicatively coupled with interstitial space 126. Thepreceding subject matter of this paragraph characterizes example 1 ofthe present disclosure.

Conduit 100 provides a compliant structure for transportation of fluids,such as cryogenic fuels, that accommodates displacements encounteredduring operation. First sensor 116, being communicatively coupled withinterstitial space 126, allows first sensor 116 to monitor conditionswithin interstitial space 126. In particular, first sensor 116 enablesdetection of leaks in corrugated inboard ply 110 by detecting changes inconditions within interstitial space 126. First weld 136 facilitateshermetical coupling of first outer collar portion 104 and first innercollar portion 106 while allowing first outer collar portion 104 to beseparately formed from and interconnected to first inner collar portion106, which enables bellows 108 to be hermetically coupled to firstcollar 102 in a simple and efficient manner. Similarly, sixth weld 137facilitates hermetical coupling of second outer collar portion 105 andsecond inner collar portion 107 while allowing second outer collarportion 105 to be separately formed from and interconnected to secondinner collar portion 107, which enables bellows 108 to be hermeticallycoupled to second collar 103 in a simple and efficient manner. Secondweld 138 promotes a strong, reliable, and sealed connection betweencorrugated inboard ply 110 and first outer collar portion 104. Thirdweld 134 promotes a strong, reliable, and sealed connection betweencorrugated outboard ply 112 and first inner collar portion 106. Fourthweld 186 promotes a strong, reliable, and sealed connection betweencorrugated inboard ply 110 and second outer collar portion 105. Fifthweld 184 promotes a strong, reliable, and sealed connection betweencorrugated outboard ply 112 and second inner collar portion 107.Communicatively coupling interstitial space 126 with first sensor 116allows leaks of fluid or gas into interstitial space 126 throughcorrugated inboard ply 110 to be detected at a location, external tofirst collar 102 and second collar 103.

Second weld 138, third weld 134, fourth weld 186, and fifth weld 184help to respectively hermetically couple first end 160 of bellows 108 tofirst collar 102 and second end 162 of bellows 108, which is oppositefirst end 160 of bellows, to second collar 103. In some examples, eachof first weld 136, second weld 138, third weld 134, fourth weld 186,fifth weld 184, and sixth weld 137 is a homogenous weld that includesfiller material. Homogenous welds are helpful when welding relativelythin parts, such as corrugated inboard ply 110 and corrugated outboardply 112. In one or more examples, the filler material is a material withproperties similar to those of the material of first outer collarportion 104, first inner collar portion 106, second outer collar portion105, and second inner collar portion 107. According to certain examples,each of first outer collar portion 104, first inner collar portion 106,second outer collar portion 105, second inner collar portion 107,corrugated inboard ply 110, and corrugated outboard ply 112 is made ofan austenitic nickel-chromium-based superalloy, such as Inconel®. Eachof corrugated inboard ply 110 and corrugated outboard ply 112 has athickness of about 0.012 inches, in some examples.

According to some examples, one or more of first outer collar portion104, first inner collar portion 106, second outer collar portion 105,and second inner collar portion 107 is manufactured using subtractivemanufacturing techniques, such as machining. In other examples, one ormore of first outer collar portion 104, first inner collar portion 106,second outer collar portion 105, and second inner collar portion 107 ismanufactured using additive manufacturing techniques. In yet otherexamples, one or more of first outer collar portion 104, first innercollar portion 106, second outer collar portion 105, and second innercollar portion 107 is manufactured using forging or casting techniques.

In some examples, first collar 102 is different than second collar 103.In one or more examples, first fluid flow port 132 of first collar 102is of a first type, for fluidly coupling to a first component, andsecond fluid flow port 133 of second collar 103 is of a second type, forfluidly coupling to a second component, different than the firstcomponent. Each of first fluid flow port 132 and second fluid flow port133 defines an aperture through which fluid flows into or out of conduit100. In some examples, one of first fluid flow port 132 or second fluidflow port 133 is a nozzle.

Bellows 108 comprises corrugations 158 that help to facilitatecompliance of bellows 108. For example, corrugations 158 allow bellows108 to expand and retract, radially and longitudinally, relative tocentral axis 180, in response to changes in internal and externalconditions relative to conduit 100 (e.g., changes in pressure,temperature, and geometry). Additionally, bellows 108 defines fluid flowchannel 128, through which fluid is flowable.

In one or more examples, first sensor 116 is any one of various sensorsused to detect the presence of a chemical or a pressure change. In oneof more examples, first sensor 116 is one or more of a micro-fuel cell,contactless oxygen sensor spots, oxygen sensor foil, and oxygen probes.

Welds are continuous or annular shaped in one or more examples.Additionally, in one or more example, welds have closed shapes. As usedherein, “hermetically coupled with a weld” with a weld means the weld iscontinuous and forms a closed shape.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, at least a part of a portion of corrugated outboard ply 112,proximate third weld 134, is closer to central axis 180 of bellows 108than third weld 134. At least a part of a portion of corrugated outboardply 112, proximate fifth weld 184, is closer to central axis 180 ofbellows 108 than fifth weld 184. The preceding subject matter of thisparagraph characterizes example 2 of the present disclosure, whereinexample 2 also includes the subject matter according to example 1,above.

At least part of a portion of corrugated outboard ply 112, proximatethird weld 134, being closer to central axis 180 of bellows 108 thanthird weld 134, ensures third weld 134 does not obstruct interstitialspace 126. Similarly, at least part of a portion of corrugated outboardply 112, proximate fifth weld 184, being closer to central axis 180 ofbellows 108 than fifth weld 184, ensures fifth weld 184 does notobstruct interstitial space 126.

Referring generally to FIG. 1A and particularly to, e.g., FIGS. 2 and 3,first collar 102 further comprises first channel 118, passing throughone of first outer collar portion 104 or first inner collar portion 106.First channel 118 is cross-sectionally circumferentially closed. Firstchannel 118 is communicatively coupled with interstitial space 126 ofbellows 108. First sensor 116 is communicatively coupled with firstchannel 118 of first collar 102. The preceding subject matter of thisparagraph characterizes example 3 of the present disclosure, whereinexample 3 also includes the subject matter according to example 1 or 2,above.

Communicatively coupling interstitial space 126 with first sensor 116,via first channel 118 passing through one of first outer collar portion104 or first inner collar portion 106, allows leaks of fluid or gas intointerstitial space 126 through corrugated inboard ply 110 to be detectedat any of various locations external to first collar 102, which helps tosimplify the assembly and design of first collar 102 of conduit 100.

As defined in relation to first channel 118, which is, for example, aport or a hole, “cross-sectionally circumferentially closed” means thatthe circumference of any cross-section of first channel 118 that lies ina plane, perpendicular to a central axis of first channel 118, has aclosed shape. A closed shape is a space that is fully enclosed by anunbroken line or contour.

Referring generally to FIG. 1A and particularly to, e.g., FIGS. 2 and 3,first channel 118 passes through first outer collar portion 104 of firstcollar 102. The preceding subject matter of this paragraph characterizesexample 4 of the present disclosure, wherein example 4 also includes thesubject matter according to example 3, above.

First channel 118, passing through first outer collar portion 104 offirst collar 102, allows first sensor 116 to be located on first outercollar portion 104, which helps to free up space on first inner collarportion 106 for attachment of sheath 130.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, the pressure in interstitial space 126 and in first channel 118is no more than 15 pounds per square inch (psi). The preceding subjectmatter of this paragraph characterizes example 5 of the presentdisclosure, wherein example 5 also includes the subject matter accordingto example 3 or 4, above.

When conduit 100 is used in space, maintaining pressure in interstitialspace 126 at or below 15 psi provides controlled separation betweencorrugated inboard ply 110 and corrugated outboard ply 112, whichprevents corrugated inboard ply 110 and corrugated outboard ply 112 frompressing against each other excessively. Preventing corrugated inboardply 110 and corrugated outboard ply 112 from pressing against each otherexcessively helps facilitate transfer, to first sensor 116, of any fluid(e.g., propellant) that has leaked into interstitial space 126.Furthermore, controlled separation between corrugated inboard ply 110and corrugated outboard ply 112 helps to reduce scuffing betweencorrugated inboard ply 110 and corrugated outboard ply 112. As usedherein, pounds per square inch (psi) is absolute pressure.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, the pressure in interstitial space 126 and in first channel 118is no more than 5 psi. The preceding subject matter of this paragraphcharacterizes example 6 of the present disclosure, wherein example 6also includes the subject matter according to example 5, above.

Maintaining pressure in interstitial space 126 at or below 5 psi ensurespressure in interstitial space 126 is not excessive when conduit 100 isused in space. Additionally, providing some pressure at or below 5 psiin interstitial space 126 provides some controlled separation betweencorrugated inboard ply 110 and corrugated outboard ply 112.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, first collar 102 further comprises first cavity 124, locatedbetween first outer collar portion 104 and first inner collar portion106. Second collar 103 further comprises second cavity 125, locatedbetween second outer collar portion 105 and second inner collar portion107. First channel 118 is communicatively coupled with first cavity 124.First cavity 124 has an annular shape and is communicatively coupledwith interstitial space 126. Second cavity 125 has an annular shape andis communicatively coupled with interstitial space 126. The precedingsubject matter of this paragraph characterizes example 7 of the presentdisclosure, wherein example 7 also includes the subject matter accordingto any one of examples 3 to 6, above.

First cavity 124, having an annular shape and being communicativelycoupled with interstitial space 126, and second cavity 125, also havingan annular shape and also being communicatively coupled withinterstitial space 126, helps to distribute fluid, leaked intointerstitial space 126 at any of various locations about a circumferenceof interstitial space 126, to first channel 118 and first sensor 116.Additionally, first cavity 124 helps to ensure path from interstitialspace 126 to first channel 118 is unobstructed.

Referring generally to FIG. 1B and particularly to, e.g., FIG. 3,conduit 100 further comprises second sensor 117. Second collar 103further comprises second channel 119, passing through one of secondouter collar portion 105 or second inner collar portion 107. Secondchannel 119 is cross-sectionally circumferentially closed. Secondchannel 119 is communicatively coupled with interstitial space 126 ofbellows 108. Second sensor 117 is communicatively coupled with secondchannel 119 of second collar 103. The preceding subject matter of thisparagraph characterizes example 8 of the present disclosure, whereinexample 8 also includes the subject matter according to example 7,above.

Communicatively coupling interstitial space 126 with second sensor 117,via second channel 119 passing through one of second outer collarportion 105 or second inner collar portion 107, allows leaks of fluid orgas into interstitial space 126 through corrugated inboard ply 110 to bedetected at any of various locations external to second collar 103,which helps to simplify the assembly and design of second collar 103 ofconduit 100. Additionally, second sensor 117, being communicativelycoupled with interstitial space 126 along with first sensor 116,promotes redundant detection of leakage through corrugated inboard ply110. In one or more examples, second sensor 117 is able to detect achange in pressure or chemical composition in interstitial space 126that is not detectable by first sensor 116 for various reasons, such as,for example, fluid or gas leaked from corrugated inboard ply 110 doesnot reach first sensor 116 or first sensor 116 is disabled.

First sensor 116 is the same type of sensor as second sensor 117 in someexamples. In other examples, first sensor 116 is a different type ofsensor than second sensor 117. In one or more examples, first sensor 116detects chemical changes in interstitial space 126, and second sensor117 detects pressure changes in interstitial space 126, or vice versa.Employing sensors of different types is helpful when a first type ofchange in interstitial space 126 is undetectable and a second type ofchange in interstitial space 126 is detectable or is more detectablethan the first type of change.

In one or more examples, second sensor 117 is any of various sensorsused to detect the presence of a chemical or a pressure change. In oneor more examples, second sensor 117 is one or more of a micro-fuel cell,contactless oxygen sensor spots, oxygen sensor foil, and oxygen probes.

Referring generally to FIG. 1B and particularly to, e.g., FIG. 3, secondchannel 119 passes through second outer collar portion 105 of secondcollar 103. The preceding subject matter of this paragraph characterizesexample 9 of the present disclosure, wherein example 9 also includes thesubject matter according to example 8, above.

Second channel 119, passing through second outer collar portion 105 ofsecond collar 103, allows second sensor 117 to be located on secondouter collar portion 105, which helps to free up space on second innercollar portion 107 for attachment of sheath 130.

Referring generally to FIG. 1B and particularly to, e.g., FIG. 3, secondsensor 117 is configured to detect a pressure change in interstitialspace 126. The preceding subject matter of this paragraph characterizesexample 10 of the present disclosure, wherein example 10 also includesthe subject matter according to example 8 or 9, above.

Pressurized fluid leaking from corrugated inboard ply 110 can cause achange in pressure in interstitial space 126. Second sensor 117, beingconfigured to detect a pressure change in interstitial space 126, allowsleakage of fluid from corrugated inboard ply 110 to be detected.Furthermore, in some examples, second sensor 117, being configured todetect a pressure change in interstitial space 126, is agnostic to thetype of fluid transmitted through conduit 100 and leaking fromcorrugated inboard ply 110, which helps to increase the versatility ofconduit 100.

Referring generally to FIG. 1B and particularly to, e.g., FIG. 3, secondsensor 117 is configured to detect a chemical change within interstitialspace 126. The preceding subject matter of this paragraph characterizesexample 11 of the present disclosure, wherein example 11 also includesthe subject matter according to example 8 or 9, above.

In one of more examples, fluid, leaking through corrugated inboard ply110, causes a change in chemical composition in interstitial space 126as the fluid enters and occupies interstitial space 126. Second sensor117, being configured to detect a change in chemical composition ininterstitial space 126, allows leakage of fluid from corrugated inboardply 110 to be detected. Furthermore, in some examples, second sensor117, being configured to detect a change in chemical composition ininterstitial space 126, is agnostic to the pressure of fluid transmittedthrough conduit 100 and pressure of fluid in interstitial space 126,which helps to increase the versatility of conduit 100.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, bellows 108 further comprises second corrugated outboard ply114. Corrugated outboard ply 112 is interposed between corrugatedinboard ply 110 and second corrugated outboard ply 114. Secondcorrugated outboard ply 114 is hermetically coupled to first innercollar portion 106 by third weld 134 and is hermetically coupled tosecond inner collar portion 107 by fifth weld 184. The preceding subjectmatter of this paragraph characterizes example 12 of the presentdisclosure, wherein example 12 also includes the subject matteraccording to any one of examples 1 to 11, above.

Third weld 134 promotes a strong, reliable, and sealed connectionbetween corrugated outboard ply 112, second corrugated outboard ply 114,and first inner collar portion 106. Fifth weld 184 promotes a strong,reliable, and sealed connection between corrugated outboard ply 112,second corrugated outboard ply 114, and second inner collar portion 107.Second corrugated outboard ply 114 provides a redundant outboard ply,which, in one or more examples, promotes fault tolerance of conduit 100by enabling conduit 100 to continue to operate if corrugated outboardply 112 fails. Additionally, second corrugated outboard ply 114 protectscorrugated outboard ply 112 from abrasions caused by objects outboard ofcorrugated outboard ply 112, such as sheath 130.

Second corrugated outboard ply 114 is made of an austeniticnickel-chromium-based superalloy, such as Inconel®, in some examples.Moreover, in certain examples, second corrugated outboard ply 114 has athickness of about 0.012 inches.

Each of third weld 134 and fifth weld 184 is a single weld, in one ormore examples. In one or more examples, third weld 134 is split up intotwo separate welds, each attaching a corresponding one of corrugatedoutboard ply 112 and second corrugated outboard ply 114 to first innercollar portion 106. Similarly, in one or more examples, fifth weld 184is split up into two separate welds each welding a corresponding one ofcorrugated outboard ply 112 and second corrugated outboard ply 114 tosecond inner collar portion 107.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, second weld 138 is offset from third weld 134 along centralaxis 180 of bellows 108. Fourth weld 186 is offset from fifth weld 184along central axis 180 of bellows 108. The preceding subject matter ofthis paragraph characterizes example 13 of the present disclosure,wherein example 13 also includes the subject matter according to any oneof examples 1 to 12, above.

Second weld 138, being offset from third weld 134 along central axis 180of bellows 108, helps to ensure first sensor 116 remains communicativelycoupled with interstitial space 126 by ensuring second weld 138 is clearof third weld 134 in axial direction along central axis 180. Fourth weld186, being offset from fifth weld 184 along central axis 180 of bellows108, helps to ensure interstitial space 126 is open to second cavity 125by ensuring fourth weld 186 is clear of fifth weld 184 in axialdirection along central axis 180.

For purposes of this disclosure, “along” means coincident with orparallel to.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, second weld 138 is offset from third weld 134 along an axis,perpendicular to central axis 180 of bellows 108, and is closer tocentral axis 180 than third weld 134. Fourth weld 186 is offset fromfifth weld 184 along an axis, perpendicular to central axis 180 ofbellows 108, and is closer to central axis 180 than fifth weld 184. Thepreceding subject matter of this paragraph characterizes example 14 ofthe present disclosure, wherein example 14 also includes the subjectmatter according to any one of examples 1 to 13, above.

Second weld 138, being offset from third weld 134 along an axis,perpendicular to central axis 180 of bellows 108 and being closer tocentral axis 180 than third weld 134, helps to ensure first sensor 116remains communicatively coupled with interstitial space 126 by ensuringsecond weld 138 is clear of third weld 134 in radial direction relativeto central axis 180. Fourth weld 186, being offset from fifth weld 184along an axis, perpendicular to central axis 180 of bellows 108 andbeing closer to central axis 180 than fifth weld 184, helps to ensureinterstitial space 126 is open to second cavity 125 by ensuring fourthweld 186 is clear of fifth weld 184 in radial direction relative tocentral axis 180.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, first weld 136 is offset from second weld 138 and third weld134 along an axis, perpendicular to central axis 180 of bellows 108, andis farther away from central axis 180 than second weld 138 or third weld134. Sixth weld 137 is offset from fourth weld 186 and fifth weld 184along an axis, perpendicular to central axis 180 of bellows 108, and isfarther away from central axis 180 than fourth weld 186 or fifth weld184. The preceding subject matter of this paragraph characterizesexample 15 of the present disclosure, wherein example 15 also includesthe subject matter according to any one of examples 1 to 14, above.

First weld 136, being offset from second weld 138 and third weld 134along an axis, perpendicular to central axis 180 of bellows 108, and isfarther away from central axis 180 than second weld 138 or third weld134, helps to ensure first sensor 116 remains communicatively coupledwith interstitial space 126 by ensuring first weld 136 is clear ofsecond weld 138 and third weld 134 in radial direction relative tocentral axis 180. Sixth weld 137, being offset from fourth weld 186 andfifth weld 184 along an axis, perpendicular to central axis 180 ofbellows 108, and is farther away from central axis 180 than fourth weld186 or fifth weld 184, helps to ensure interstitial space 126 is open tosecond cavity 125 by ensuring sixth weld 137 is clear of fourth weld 186and fifth weld 184 in radial direction relative to central axis 180.

Referring generally to 1A and 1B and particularly to, e.g., FIGS. 2 and3, first weld 136 is offset from second weld 138 and third weld 134along central axis 180 of bellows 108. Sixth weld 137 is offset fromfourth weld 186 and fifth weld 184 along central axis 180 of bellows108. The preceding subject matter of this paragraph characterizesexample 16 of the present disclosure, wherein example 16 also includesthe subject matter according to any one of examples 1 to 15, above.

First weld 136, being offset from second weld 138 and third weld 134along central axis 180 of bellows 108, helps to ensure first sensor 116remains communicatively coupled with interstitial space 126 by ensuringfirst weld 136 is clear of second weld 138 and third weld 134 in axialdirection along central axis 180. Sixth weld 137, being offset fromfourth weld 186 and fifth weld 184 along central axis 180 of bellows108, helps to ensure interstitial space 126 is open to second cavity 125by ensuring sixth weld 137 is clear of fourth weld 186 and fifth weld184 in axial direction along central axis 180.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, conduit 100 further comprises sheath 130 that comprisesreinforcement layer 187. Corrugated outboard ply 112 is interposedbetween sheath 130 and central axis 180. The preceding subject matter ofthis paragraph characterizes example 17 of the present disclosure,wherein example 17 also includes the subject matter according to any oneof examples 1 to 16, above.

Reinforcement layer 187 of sheath 130 helps to protect bellows 108 fromexternal objects.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, sheath 130 is coupled to first inner collar portion 106 offirst collar 102 and to second inner collar portion 107 of second collar103. The preceding subject matter of this paragraph characterizesexample 18 of the present disclosure, wherein example 18 also includesthe subject matter according to example 17, above.

Coupling sheath 130 to first inner collar portion 106 of first collar102 and second inner collar portion 107 of second collar 103 ensuresentirety of outer periphery of bellows 108 is protected. Additionally,coupling sheath 130 to first inner collar portion 106 of first collar102 and second inner collar portion 107 of second collar 103 allowssheath 130 to be coupled to first inner collar portion 106 and secondinner collar portion 107 before first outer collar portion 104 ishermetically coupled to first inner collar portion 106 by first weld 136and before second outer collar portion 105 is hermetically coupled tosecond inner collar portion 107 by sixth weld 137.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, sheath 130 is movable relative to first inner collar portion106 of first collar 102 and relative to second inner collar portion 107of second collar 103. The preceding subject matter of this paragraphcharacterizes example 19 of the present disclosure, wherein example 19also includes the subject matter according to example 18, above.

Sheath 130, being movable relative to first inner collar portion 106 offirst collar 102 and relative to second inner collar portion 107 ofsecond collar 103, facilitates compliance of sheath 130 relative tobellows 108 by allowing sheath 130 to move with bellows 108 during useof conduit 100.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, sheath 130 is translatable along central axis 180 relative tofirst inner collar portion 106 of first collar 102 and relative tosecond inner collar portion 107 of second collar 103. The precedingsubject matter of this paragraph characterizes example 20 of the presentdisclosure, wherein example 20 also includes the subject matteraccording to example 19, above.

Sheath 130, being translatable along central axis 180 relative to firstinner collar portion 106 of first collar 102 and relative to secondinner collar portion 107 of second collar 103, accommodates lengthening(e.g., expansion) and shortening (e.g., contraction) of bellows 108during use of conduit 100.

In some examples, sheath 130 is coupled to each of first inner collarportion 106 and second inner collar portion 107 by pins 169 engaged withslots 167 formed in first inner collar portion 106 and second innercollar portion 107. Each one of slots 167 is elongated along centralaxis 180. Each pin 169 passes through a corresponding end of sheath 130and passes into a corresponding one of slots 167. Sheath 130 isnon-movably fixed to pins 169, but each pin 169 is allowed totranslatably move along the corresponding one of slots 167, whichfacilitates translational movement of sheath 130 along central axis 180relative to first inner collar portion 106 and second inner collarportion 107. According to one example, each one of slots 167 has awidth, substantially equal to a width of pins 169, which prevents pins169, and thus sheath 130, from rotating about central axis 180 relativeto first inner collar portion 106 and second inner collar portion 107.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, sheath 130 is rotatable about central axis 180 relative tofirst inner collar portion 106 of first collar 102 and relative tosecond inner collar portion 107 of second collar 103. The precedingsubject matter of this paragraph characterizes example 21 of the presentdisclosure, wherein example 21 also includes the subject matteraccording to example 19 or 20, above.

Sheath 130, being rotatable about central axis 180 relative to firstinner collar portion 106 of first collar 102 and relative to secondinner collar portion 107 of second collar 103, accommodates rotation ofbellows 108 about central axis 180 during use of conduit 100.

In some examples, slots 167 formed in first inner collar portion 106 andsecond inner collar portion 107, are at least partially annular.Accordingly, pins 169, when engaged with slots 167, are allowed to movetranslatably along slots 167 in a circumferential direction relative tofirst inner collar portion 106 and second inner collar portion 107. Suchmovement of pins 169 within slots 167 facilitates rotational movement ofsheath 130 about central axis 180 relative to first inner collar portion106 and second inner collar portion 107. According to one example, eachone of slots 167 has a width that is substantially equal to a width ofeach one of pins 169, which prevents pins 169, and thus sheath 130, fromtranslating along central axis 180 relative to first inner collarportion 106 and second inner collar portion 107. However, in at leastone other example, each one of slots 167 has a width that is greaterthan the width of each one of pins 169. Each one of slots 167, having awidth that is greater than the width of each one of pins 169,accommodates both rotational movement of sheath 130 about central axis180 relative to first inner collar portion 106 and second inner collarportion 107 and translational movement of sheath 130 along central axis180 relative to first inner collar portion 106 and second inner collarportion 107.

Referring generally to 1A and 1B and particularly to, e.g., FIGS. 2 and3, sheath 130 further comprises low-friction layer 189, interposedbetween reinforcement layer 187 of sheath 130 and corrugated outboardply 112 of bellows 108. Low-friction layer 189 of sheath 130 has asurface roughness lower than that of reinforcement layer 187 of sheath130. The preceding subject matter of this paragraph characterizesexample 22 of the present disclosure, wherein example 22 also includesthe subject matter according to any one of examples 17 to 21, above.

Low-friction layer 189 of sheath 130 helps to reduce abrasions betweenreinforcement layer 187 and bellows 108, particularly when bellows 108moves relative to sheath 130.

According to some examples, the surface roughness of low-friction layer189 corresponds with a coefficient-of-friction of the low-friction layer189 between 0.05 and 0.1, and the surface roughness of reinforcementlayer 187 corresponds with a coefficient-of-friction that is higher thanthat of low-friction layer 189. Low-friction layer 189 of sheath 130 ismade of a low-friction material, such as polytetrafluoroethylene,Nylon®, Teflon®, and the like, in some examples. Reinforcement layer 187is made of a high-abrasion-resistance material, such as fiberglass,aramid, stainless steel (mesh), in certain examples.

Referring generally to FIGS. 1A and 1B and particularly to, e.g., FIGS.2 and 3, low-friction layer 189 of sheath 130 is in contact withcorrugated outboard ply 112 of bellows 108. The preceding subject matterof this paragraph characterizes example 23 of the present disclosure,wherein example 23 also includes the subject matter according to example22, above.

Low-friction layer 189 of sheath 130, being in contact with corrugatedoutboard ply 112, ensures that the outside diameter of sheath 130 is assmall as possible for use in confined spaces.

Referring generally to 1A and 1B and particularly to, e.g., FIGS. 2 and3, bellows 108 further comprises second corrugated outboard ply 114.Corrugated outboard ply 112 is interposed between corrugated inboard ply110 and second corrugated outboard ply 114. Second corrugated outboardply 114 is hermetically coupled to first inner collar portion 106 bythird weld 134 and is hermetically coupled to second inner collarportion 107 by fifth weld 184. Low-friction layer 189 of sheath 130 isin contact with second corrugated outboard ply 114 of bellows 108. Thepreceding subject matter of this paragraph characterizes example 24 ofthe present disclosure, wherein example 24 also includes the subjectmatter according to example 22 or 23, above.

Low-friction layer 189 of sheath 130, being in contact with secondcorrugated outboard ply 114, ensures second corrugated outboard ply 114is protected against impacts with external objects and abrasions causedby contact between sheath 130 and bellows 108.

Referring generally to FIG. 1A and particularly to, e.g., FIGS. 2 and 3,first sensor 116 is configured to detect a pressure change ininterstitial space 126. The preceding subject matter of this paragraphcharacterizes example 25 of the present disclosure, wherein example 25also includes the subject matter according to any one of examples 1 to24, above.

First sensor 116, being configured to detect a pressure change ininterstitial space 126, allows leakage of fluid from corrugated inboardply 110 to be detected. Furthermore, in some examples, first sensor 116,being configured to detect a pressure change in interstitial space 126,is agnostic to the type of fluid transmitted through conduit 100 andleaking from corrugated inboard ply 110, which helps to increase theversatility of conduit 100.

Referring generally to FIG. 1A and particularly to, e.g., FIGS. 2 and 3,first sensor 116 is configured to detect a chemical change withininterstitial space 126. The preceding subject matter of this paragraphcharacterizes example 26 of the present disclosure, wherein example 26also includes the subject matter according to any one of examples 1 to24, above.

First sensor 116, being configured to detect a change in chemicalcomposition in interstitial space 126, allows leakage of fluid fromcorrugated inboard ply 110 to be detected. Furthermore, in someexamples, first sensor 116, being configured to detect a change inchemical composition in interstitial space 126, is agnostic to thepressure of fluid transmitted through conduit 100 and pressure of fluidin interstitial space 126, which helps to increase the versatility ofconduit 100.

Referring generally to FIGS. 1A and 1C and particularly to, e.g., FIG.12, first sensor 116 comprises first chamber 190, containing firstreactant 198. First sensor 116 further comprises second chamber 192,containing second reactant 199, isolated from first chamber 190, andcommunicatively coupled with interstitial space 126. First reactant 198is identical to second reactant 199. The preceding subject matter ofthis paragraph characterizes example 27 of the present disclosure,wherein example 27 also includes the subject matter according to any oneof examples 1 to 24 and 26, above.

First reactant 198, being the same as second reactant 199, facilitatescontrasting visual conditions if first reactant 198 reacts with gasleaking into interstitial space 126. Because first reactant 198 andsecond reactant 199 are the same, the contrasting visual conditionsoccur despite changes in lighting conditions or discoloration of firstreactant 198 and second reactant 199 due to time or atmosphericconditions. Contrasting visual conditions is enhanced by configuringfirst chamber 190 and second chamber 192 in a side-by-sideconfiguration.

In some examples, first reactant 198 and second reactant 199 ispalladium oxide, which is configured to react (e.g., discolor) in thepresence of hydrogen. First sensor 116 further comprises permeablebarrier 194 and impermeable barrier 196. Second chamber 192 is isolatedfrom first chamber 190 by impermeable barrier 196, which is configuredto prevent passage of first reactant 198 and second reactant 199 intosecond chamber 192 and first chamber 190, respectively, and to preventpassage of fluid into interstitial space 126 from second chamber 192 tofirst chamber 190. Permeable barrier 194 is configured to preventpassage of second reactant 199 from second chamber 192 to first channel118 and interstitial space 126 and to allow passage of fluid, ininterstitial space 126, from interstitial space 126 to second chamber192.

Referring generally to FIG. 1A and particularly to, e.g., FIGS. 2 and 3,conduit 100 for transporting a fluid is disclosed. Conduit 100 comprisesfirst collar 102 that comprises first outer collar portion 104, firstinner collar portion 106, and first weld 136, hermetically couplingfirst outer collar portion 104 and first inner collar portion 106.Conduit 100 further comprises bellows 108 that comprises central axis180, corrugated outboard ply 112, corrugated inboard ply 110, interposedbetween corrugated outboard ply 112 and central axis 180, andinterstitial space 126, interposed between corrugated inboard ply 110and corrugated outboard ply 112. Conduit 100 also comprises second weld138, hermetically coupling corrugated inboard ply 110 and first outercollar portion 104. Conduit 100 additionally comprises third weld 134,hermetically coupling corrugated outboard ply 112 and first inner collarportion 106. Conduit 100 further comprises first sensor 116,communicatively coupled with interstitial space 126. The precedingsubject matter of this paragraph characterizes example 28 of the presentdisclosure.

Conduit 100 provides a compliant structure for the transmission offluids, such as cryogenic fuels, that accommodates displacementsencountered during operation. First sensor 116, being communicativelycoupled with interstitial space 126, allows first sensor 116 to monitorconditions within interstitial space 126. In particular, first sensor116 enables detection of leaks in corrugated inboard ply 110 bydetecting changes in conditions within interstitial space 126. Firstweld 136 facilitates hermetical coupling of first outer collar portion104 and first inner collar portion 106 while allowing first outer collarportion 104 to be separately formed from and interconnected to firstinner collar portion 106, which enables bellows 108 to be hermeticallycoupled to first collar 102 in a simple and efficient manner. Secondweld 138 promotes a strong, reliable, and sealed connection betweencorrugated inboard ply 110 and first outer collar portion 104. Thirdweld 134 promotes a strong, reliable, and sealed connection betweencorrugated outboard ply 112 and first inner collar portion 106.Communicatively coupling interstitial space 126 with first sensor 116allows leaks of fluid or gas into interstitial space 126 throughcorrugated inboard ply 110 to be detected at a location, external tofirst collar 102.

Referring generally to FIGS. 13A-13E and particularly to, e.g., FIGS.4-12, method 200 of fabricating conduit 100 is disclosed. Method 200comprises (block 202) attaching first tubular-outboard-ply end 149 oftubular outboard ply 113 to first inner collar portion 106 of firstcollar 102 with third weld 134. Method 200 further comprises (block 204)attaching second tubular-outboard-ply end 147 of tubular outboard ply113, which is axially opposite first tubular-outboard-ply end 149 oftubular outboard ply 113, to second inner collar portion 107 of secondcollar 103 with fifth weld 184. Method 200 also comprises (block 206)inserting tubular inboard ply 111 into tubular outboard ply 113 andadvancing tubular inboard ply 111 along an interior of tubular outboardply 113 until first tubular-inboard-ply end 157 of tubular inboard ply111 protrudes first distance D1 past first inner collar portion 106, andsecond tubular-inboard-ply end 159 protrudes second distance D2 pastsecond inner collar portion 107. First distance D1 is greater than firstpredetermined distance PD1 and second distance D2 is greater than secondpredetermined distance PD1. Method 200 additionally comprises (block208) simultaneously corrugating tubular inboard ply 111 and tubularoutboard ply 113 to form bellows 108, having central axis 180 andcomprising corrugated outboard ply 112, corrugated inboard ply 110, andinterstitial space 126, interposed between corrugated inboard ply 110and corrugated outboard ply 112. Corrugated outboard ply 112 is formedfrom tubular outboard ply 113, and corrugated inboard ply 110 is formedfrom tubular inboard ply 111. Method 200 further comprises (block 210)trimming first corrugated-inboard-ply end 151 of corrugated inboard ply110, corresponding to first tubular-inboard-ply end 157 of tubularinboard ply 111, to create trimmed first corrugated-inboard-ply end 156that protrudes first predetermined distance PD1 past first inner collarportion 106. Method 200 also comprises (block 212) trimming secondcorrugated-inboard-ply end 153 of corrugated inboard ply 110,corresponding to second tubular-inboard-ply end 159 of tubular inboardply 111, to create trimmed second corrugated-inboard-ply end 170 thatprotrudes second predetermined distance PD2 past second inner collarportion 107. Method 200 additionally comprises (block 214)interconnecting first inner collar portion 106 and first outer collarportion 104 of first collar 102 with first weld 136. Method 200 furthercomprises (block 216) interconnecting second inner collar portion 107and second outer collar portion 105 of second collar 103 with sixth weld137. Method 200 also comprises (block 218) attaching trimmed firstcorrugated-inboard-ply end 156 of corrugated inboard ply 110 to firstouter collar portion 104 with second weld 138. Method 200 additionallycomprises (block 220) attaching trimmed second corrugated-inboard-plyend 170 of corrugated inboard ply 110 to second outer collar portion 105with fourth weld 186. Method 200 further comprises (block 222)communicatively coupling first sensor 116 with interstitial space 126.The preceding subject matter of this paragraph characterizes example 29of the present disclosure.

Method 200 facilitates fabrication of conduit 100 in an efficient andsimple manner. Conduit 100 provides a compliant structure fortransmission of fluids, such as cryogenic fuels, that accommodatesdisplacements encountered during operation. Simultaneously corrugatingtubular outboard ply 113 and tubular inboard ply 111 to form bellows 108promotes corrugations 158 in corrugated inboard ply 110 and corrugatedoutboard ply 112 of bellows 108 that are complementary to each other.First sensor 116, being communicatively coupled with interstitial space126, allows first sensor 116 to monitor conditions within interstitialspace 126. First weld 136 facilitates hermetical coupling of first outercollar portion 104 and first inner collar portion 106 while allowingfirst outer collar portion 104 to be separately formed from andinterconnected to first inner collar portion 106, which enables bellows108 to be hermetically coupled to first collar 102 in a simple andefficient manner. Similarly, sixth weld 137 facilitates hermeticalcoupling of second outer collar portion 105 and second inner collarportion 107 while allowing second outer collar portion 105 to beseparately formed from and interconnected to second inner collar portion107, which enables bellows 108 to be hermetically coupled to secondcollar 103 in a simple and efficient manner. Second weld 138 promotes astrong, reliable, and sealed connection between corrugated inboard ply110 and first outer collar portion 104. Third weld 134 promotes astrong, reliable, and sealed connection between corrugated outboard ply112 and first inner collar portion 106. Fourth weld 186 promotes astrong, reliable, and sealed connection between corrugated inboard ply110 and second outer collar portion 105. Fifth weld 184 promotes astrong, reliable, and sealed connection between corrugated outboard ply112 and second inner collar portion 107. Advancing tubular inboard ply111 along an interior of tubular outboard ply 113 until firsttubular-inboard-ply end 157 of tubular inboard ply 111 protrudes firstdistance D1 past first inner collar portion 106, and secondtubular-inboard-ply end 159 protrudes second distance D2 past secondinner collar portion 107 accommodates the reduction in the length oftubular inboard ply 111 after tubular inboard ply 111 is corrugated.Trimming first corrugated-inboard-ply end 151 of corrugated inboard ply110 and trimming second corrugated-inboard-ply end 153 of corrugatedinboard ply 110 promotes achieving a desired length of corrugatedinboard ply 110 after corrugation of tubular inboard ply 111.Communicatively coupling interstitial space 126 with first sensor 116allows leaks of fluid or gas into interstitial space 126 throughcorrugated inboard ply 110 to be detected at a location external tofirst collar 102 and second collar 103.

After corrugating tubular outboard ply 113, first tubular-outboard-plyend 149 of tubular outboard ply 113 becomes firstcorrugated-outboard-ply end 146 of corrugated outboard ply 112 andsecond tubular-outboard-ply end 147 of tubular outboard ply 113 becomessecond corrugated-outboard-ply end 171 of corrugated outboard ply 112.

Referring generally to FIG. 13A and particularly to, e.g., FIG. 6,according to method 200, inserting tubular inboard ply 111 into tubularoutboard ply 113 comprises (block 246) inserting firsttubular-inboard-ply end 157 of tubular inboard ply 111 into secondtubular-outboard-ply end 147 of tubular outboard ply 113. The precedingsubject matter of this paragraph characterizes example 30 of the presentdisclosure, wherein example 30 also includes the subject matteraccording to example 29, above.

Inserting first tubular-inboard-ply end 157 of tubular inboard ply 111into second tubular-outboard-ply end 147 of tubular outboard ply 113allows first tubular-inboard-ply end 157 to be positioned first distanceD1 past first inner collar portion 106 in an efficient manner.

Referring generally to FIGS. 13B and 13C and particularly to, e.g.,FIGS. 6-8 and 11, according to method 200, (block 250) first innercollar portion 106 is interconnected with first outer collar portion 104and (block 258) second inner collar portion 107 is interconnected withsecond outer collar portion 105 after tubular inboard ply 111 isadvanced along interior of tubular outboard ply 113 and after tubularinboard ply 111 and tubular outboard ply 113 are simultaneouslycorrugated. The preceding subject matter of this paragraph characterizesexample 31 of the present disclosure, wherein example 31 also includesthe subject matter according to example 29 or 30, above.

Interconnecting first inner collar portion 106 with first outer collarportion 104 and interconnecting second inner collar portion 107 withsecond outer collar portion 105, after tubular inboard ply 111 isadvanced along interior of tubular outboard ply 113 and after tubularinboard ply 111 and tubular outboard ply 113 are simultaneouslycorrugated, promotes ease in trimming first corrugated-inboard-ply end151 and second corrugated-inboard-ply end 153 to create trimmed firstcorrugated-inboard-ply end 156 and trimmed second corrugated-inboard-plyend 170, as it is possible to position first outer collar portion 104and second outer collar portion 105 away from and out of the way offirst inner collar portion 106 and second inner collar portion 107during the trimming operations.

Referring generally to FIG. 13A and particularly to, e.g., FIGS. 5-7,according to method 200, (block 248) tubular inboard ply 111 is insertedinto tubular outboard ply 113 after first tubular-outboard-ply end 149of tubular outboard ply 113 is attached to first inner collar portion106 and after second tubular-outboard-ply end 147 of tubular outboardply 113 is attached to second inner collar portion 107. The precedingsubject matter of this paragraph characterizes example 32 of the presentdisclosure, wherein example 32 also includes the subject matteraccording to example 31, above.

Inserting tubular inboard ply 111 into tubular outboard ply 113 afterfirst tubular-outboard-ply end 149 of tubular outboard ply 113 isattached to first inner collar portion 106 and after secondtubular-outboard-ply end 147 of tubular outboard ply 113 is attached tosecond inner collar portion 107 promotes ease in welding firsttubular-outboard-ply end 149 to first inner collar portion 106 andwelding second tubular-outboard-ply end 147 to second inner collarportion 107 by reducing obstructions to the welding site.

Referring generally to FIGS. 13C and 13D and particularly to, e.g.,FIGS. 11 and 12, according to method 200, (block 266) trimmed firstcorrugated-inboard-ply end 156 of corrugated inboard ply 110 is attachedto first outer collar portion 104 after first inner collar portion 106and first outer collar portion 104 are interconnected with first weld136, and (block 278) trimmed second corrugated-inboard-ply end 170 ofcorrugated inboard ply 110 is attached to second outer collar portion105 after second inner collar portion 107 and second outer collarportion 105 are interconnected with sixth weld 137. The precedingsubject matter of this paragraph characterizes example 33 of the presentdisclosure, wherein example 33 also includes the subject matteraccording to example 32, above.

Attaching trimmed first corrugated-inboard-ply end 156 of corrugatedinboard ply 110 to first outer collar portion 104 after first innercollar portion 106 and first outer collar portion 104 are interconnectedwith first weld 136, and attaching trimmed second corrugated-inboard-plyend 170 of corrugated inboard ply 110 to second outer collar portion 105after second inner collar portion 107 and second outer collar portion105 are interconnected with sixth weld 137 allows first outer collarportion 104 and second outer collar portion 105 to be properlypositioned to receive trimmed first corrugated-inboard-ply end 156 andtrimmed second corrugated-inboard-ply end 170, respectively.

Referring generally to FIG. 13D and particularly to, e.g., FIGS. 2, 3,and 12, according to method 200, first sensor 116 is communicativelycoupled with interstitial space 126 via first channel 118, passingthrough one of first inner collar portion 106 or first outer collarportion 104. First channel 118 is cross-sectionally circumferentiallyclosed. The preceding subject matter of this paragraph characterizesexample 34 of the present disclosure, wherein example 34 also includesthe subject matter according to any one of examples 29 to 33, above.

Communicatively coupling interstitial space 126 with first sensor 116,via first channel 118 passing through one of first outer collar portion104 or first inner collar portion 106, allows leaks of fluid or gas intointerstitial space 126 through corrugated inboard ply 110 to be detectedat any of various locations external to first collar 102, which helps tosimplify the assembly and design of first collar 102 of conduit 100.

Referring generally to FIG. 13D and particularly to, e.g., FIG. 3,method 200 further comprises (block 224) communicatively coupling secondsensor 117 with interstitial space 126 via second channel 119, passingthrough one of second inner collar portion 107 or second outer collarportion 105. Second channel 119 is cross-sectionally circumferentiallyclosed. The preceding subject matter of this paragraph characterizesexample 35 of the present disclosure, wherein example 35 also includesthe subject matter according to example 34, above.

Communicatively coupling interstitial space 126 with second sensor 117,via second channel 119 passing through one of second outer collarportion 105 or second inner collar portion 107, allows leaks of fluid orgas into interstitial space 126 through corrugated inboard ply 110 to bedetected at any of various locations external to second collar 103,which helps to simplify the assembly and design of second collar 103 ofconduit 100. Additionally, second sensor 117, being communicativelycoupled with interstitial space 126 along with first sensor 116,promotes redundant detection of leakage through corrugated inboard ply110. In one or more examples, second sensor 117 is able to detect achange in pressure or chemical composition in interstitial space 126that is not detectable by first sensor 116 for various reasons, such as,for example, when fluid, leaking through corrugated inboard ply 110,does not reach first sensor 116 or when first sensor 116 is disabled.

Referring generally to FIG. 13D and particularly to, e.g., FIG. 12,method 200 further comprises (block 226) reducing pressure ininterstitial space 126 to below atmospheric pressure after first sensor116 is communicatively coupled with interstitial space 126. Thepreceding subject matter of this paragraph characterizes example 36 ofthe present disclosure, wherein example 36 also includes the subjectmatter according to any one of examples 29 to 35, above.

Reducing pressure in interstitial space 126 to below atmosphericpressure helps to prevent excessive separation of corrugated inboard ply110 and corrugated outboard ply 112 when conduit 100 is used in outerspace or outside of the Earth's atmosphere. Furthermore, reducingpressure in interstitial space 126 to below atmospheric pressurepromotes a controlled separation of corrugated inboard ply 110 andcorrugated outboard ply 112 when conduit 100 is used in outer space oroutside of the Earth's atmosphere. Such a controlled separation helps tokeep corrugated inboard ply 110 and corrugated outboard ply 112 fromexcessively pressing against each other, which could impede the transferof fluid or gas e.g., propellant from reaching channel 118 and firstsensor 116. Additionally, controlled separation helps to reduce damagee.g., scuffing caused by contact between corrugated inboard ply 110 andcorrugated outboard ply 112.

Referring generally to FIG. 13D and particularly to, e.g., FIG. 12,according to method 200, (block 288) pressure in interstitial space 126is reduced by creating a pressure gradient across vacuum port 120,communicatively coupled with interstitial space 126. The precedingsubject matter of this paragraph characterizes example 37 of the presentdisclosure, wherein example 37 also includes the subject matteraccording to example 36, above.

Vacuum port 120 enables pressure in interstitial space 126 to be reducedfrom location external to first collar 102 after first sensor 116 iscommunicatively coupled with interstitial space 126. Pressure gradientacross vacuum port 120 is created by communicatively coupling pump 197to vacuum port 120.

Referring generally to FIG. 13E and particularly to, e.g., FIGS. 2, 3,and 12, method 200 further comprises (block 228) sealing vacuum port120, after pressure in interstitial space 126 is reduced, by closingpinch-off tube 140. The preceding subject matter of this paragraphcharacterizes example 38 of the present disclosure, wherein example 38also includes the subject matter according to example 37, above.

Pinch-off tube 140 provides quick and easy sealing of vacuum port 120after pressure is reduced. Pump 197 is communicatively coupled to vacuumport 120 by pinch-off tube 140. In some examples, pinch-off tube 140 hasa sufficient length that is conducive to multiple pressure-reduction andclosing operations.

Referring generally to FIGS. 13A and 13E and particularly to, e.g.,FIGS. 4 and 5, method 200 further comprises (block 230) flaring firsttubular-outboard-ply end 149 of tubular outboard ply 113 to create firstflared portion 148 of first tubular-outboard-ply end 149. The step ofattaching first tubular-outboard-ply end 149 of tubular outboard ply 113to first inner collar portion 106 comprises (block 242) attaching firstflared portion 148 of first tubular-outboard-ply end 149 to firstbeveled weld-joint recess 144 of first inner collar portion 106 withthird weld 134. Method 200 additionally comprises (block 232) flaringsecond tubular-outboard-ply end 147 of tubular outboard ply 113 tocreate second flared portion 181 of second tubular-outboard-ply end 147.The step of attaching second tubular-outboard-ply end 147 of tubularoutboard ply 113 to second inner collar portion 107 comprises (block244) attaching second flared portion 181 of second tubular-outboard-plyend 147 to second beveled weld-joint recess 161 of second inner collarportion 107 with fifth weld 184. The preceding subject matter of thisparagraph characterizes example 39 of the present disclosure, whereinexample 39 also includes the subject matter according to any one ofexamples 29 to 38, above.

Flaring first tubular-outboard-ply end 149 of tubular outboard ply 113to create first flared portion 148 of first tubular-outboard-ply end 149and attaching first flared portion 148 of first tubular-outboard-ply end149 to first beveled weld-joint recess 144 of first inner collar portion106 with third weld 134 helps to weld first tubular-outboard-ply end 149to first inner collar portion 106 without third weld 134 obstructinginterstitial space 126 or obstructing insertion of tubular inboard ply111 into tubular outboard ply 113. Flaring second tubular-outboard-plyend 147 of tubular outboard ply 113 to create second flared portion 181of second tubular-outboard-ply end 147 and attaching second flaredportion 181 of second tubular-outboard-ply end 147 to second beveledweld-joint recess 161 of second inner collar portion 107 with fifth weld184 helps to weld second tubular-outboard-ply end 147 to second innercollar portion 107 without fifth weld 184 obstructing interstitial space126 or obstructing insertion of tubular inboard ply 111 into tubularoutboard ply 113.

Referring generally to FIG. 13E and particularly to, e.g., FIGS. 5 and8, method 200 further comprises (block 234) attaching firstsecond-tubular-outboard-ply end 174 of second tubular outboard ply 115to first inner collar portion 106 with third weld 134. Method 200additionally comprises (block 236) attaching secondsecond-tubular-outboard-ply end 176 of second tubular outboard ply 115,which is axially opposite first second-tubular-outboard-ply end 174 ofsecond tubular outboard ply 115, to second inner collar portion 107 ofsecond collar 103 with fifth weld 184. Method 200 also comprises (block238) corrugating second tubular outboard ply 115 simultaneously withtubular inboard ply 111 and tubular outboard ply 113 to form bellows108, which further comprises second corrugated outboard ply 114. Tubularoutboard ply 113 is interposed between tubular inboard ply 111 andsecond tubular outboard ply 115. Second corrugated outboard ply 114 isformed from second tubular outboard ply 115. The preceding subjectmatter of this paragraph characterizes example 40 of the presentdisclosure, wherein example 40 also includes the subject matteraccording to any one of examples 29 to 39, above.

Second corrugated outboard ply 114 provides a redundant outboard ply,which promotes fault tolerance of conduit 100 by enabling conduit 100 tocontinue to operate if corrugated outboard ply 112 fails. Additionally,second corrugated outboard ply 114 protects corrugated outboard ply 112from abrasions caused by objects outboard of corrugated outboard ply112, such as sheath 130.

After corrugating second tubular outboard ply 115, firstsecond-tubular-outboard-ply end 174 of second tubular outboard ply 115becomes first second-corrugated-outboard-ply end 172 of secondcorrugated outboard ply 114 and second second-tubular-outboard-ply end176 of second tubular outboard ply 115 becomes secondsecond-corrugated-outboard-ply end 177 of second corrugated outboard ply114.

In one or more examples, method 200 also comprises flaring firstsecond-tubular-outboard-ply end 174 of second tubular outboard ply 115to create third flared portion 178 of first second-tubular-outboard-plyend 174. The step of attaching first second-tubular-outboard-ply end 174of second tubular outboard ply 115 to first inner collar portion 106comprises attaching third flared portion 178 to first beveled weld-jointrecess 144 with third weld 134. Method 200 additionally comprisesflaring second second-tubular-outboard-ply end 176 of second tubularoutboard ply 115 to create fourth flared portion 182 of second tubularoutboard ply 115. The step of attaching secondsecond-tubular-outboard-ply end 176 of second tubular outboard ply 115to second inner collar portion 107 comprises attaching fourth flaredportion 182 to second beveled weld-joint recess 161 with fifth weld 184.

Referring generally to FIGS. 13C and 13D and particularly to, e.g.,FIGS. 10-12, according to method 200, first outer collar portion 104 offirst collar 102 comprises first annular weld-joint recess 145. Secondouter collar portion 105 of second collar 103 comprises second annularweld-joint recess 163. Trimmed first corrugated-inboard-ply end 156 ofcorrugated inboard ply 110 is attached to first annular weld-jointrecess 145 of first outer collar portion 104 by second weld 138. Trimmedsecond corrugated-inboard-ply end 170 of corrugated inboard ply 110 isattached to second annular weld-joint recess 163 of second outer collarportion 105 by fourth weld 186. The preceding subject matter of thisparagraph characterizes example 41 of the present disclosure, whereinexample 41 also includes the subject matter according to any one ofexamples 29 to 40, above.

First annular weld-joint recess 145 helps to receive, retain, and aligntrimmed first corrugated-inboard-ply end 156 of corrugated inboard ply110 for welding to first outer collar portion 104. Similarly, secondannular weld-joint recess 163 helps to receive, retain, and aligntrimmed first corrugated-inboard-ply end 156 of corrugated inboard ply110 for welding to second outer collar portion 105.

Referring generally to FIGS. 13B and 13C and particularly to, e.g.,FIGS. 10 and 11, according to method 200, first weld-joint groove 142 isdefined between first outer collar portion 104 and first inner collarportion 106. Second weld-joint groove 143 is defined between secondouter collar portion 105 and second inner collar portion 107. Firstinner collar portion 106 is attached to first outer collar portion 104by filling first weld-joint groove 142 with first weld 136. Second innercollar portion 107 is attached to second outer collar portion 105 byfilling second weld-joint groove 143 with sixth weld 137. The precedingsubject matter of this paragraph characterizes example 42 of the presentdisclosure, wherein example 42 also includes the subject matteraccording to any one of examples 29 to 41, above.

First weld-joint groove 142 and second weld-joint groove 143 promote astrong, reliable, and sealed connection between first outer collarportion 104 and first inner collar portion 106 and between second outercollar portion 105 and second inner collar portion 107, respectively, byfacilitating placement and containment of the filler material of firstweld 136 and sixth weld 137, respectively.

Referring generally to FIG. 13E and particularly to, e.g., FIGS. 2, 3,11, and 12, method 200 further comprises (block 240) coupling sheath 130to first inner collar portion 106 of first collar 102 and second innercollar portion 107 of second collar 103 before first inner collarportion 106 is interconnected with first outer collar portion 104 withfirst weld 136 and before second inner collar portion 107 isinterconnected with second outer collar portion 105 with sixth weld 137.Corrugated outboard ply (112) is interposed between sheath 130 andcentral axis 180 of bellows 108. The preceding subject matter of thisparagraph characterizes example 43 of the present disclosure, whereinexample 43 also includes the subject matter according to any one ofexamples 29 to 42, above.

Sheath 130 helps to protect bellows 108 from external objects. Sheath130 is slid over one of first inner collar portion 106 or second innercollar portion 107 into a position for coupling to first inner collarportion 106 and second inner collar portion 107. Coupling sheath 130 tofirst inner collar portion 106 of first collar 102 and second innercollar portion 107 of second collar 103 before first inner collarportion 106 is interconnected with first outer collar portion 104 withfirst weld 136 and before second inner collar portion 107 isinterconnected with second outer collar portion 105 with sixth weld 137enables sheath 130 to be positioned for coupling to first inner collarportion 106 and second inner collar portion 107 before first weld 136and sixth weld 137 obstruct slidable access of sheath 130 to first innercollar portion 106 and second inner collar portion 107.

Referring generally to FIGS. 13C and 13D and particularly to, e.g.,FIGS. 2 and 3, according to method 200, second weld 138 is offset fromthird weld 134 along central axis 180 of bellows 108 and fourth weld 186is offset from fifth weld 184 along central axis 180 of bellows 108. Thepreceding subject matter of this paragraph characterizes example 44 ofthe present disclosure, wherein example 44 also includes the subjectmatter according to any one of examples 29 to 43, above.

Second weld 138, being offset from third weld 134 along central axis 180of bellows 108, helps to ensure first sensor 116 remains communicativelycoupled with interstitial space 126 by ensuring second weld 138 is clearof third weld 134 in axial direction along central axis 180. Fourth weld186, being offset from fifth weld 184 along central axis 180 of bellows108, helps to ensure interstitial space 126 is open to second cavity 125by ensuring fourth weld 186 is clear of fifth weld 184 in axialdirection along central axis 180.

Referring generally to FIGS. 13C and 13D and particularly to, e.g.,FIGS. 2 and 3, according to method 200, second weld 138 is offset fromthird weld 134 along an axis, perpendicular to central axis 180 ofbellows 108, and is closer to central axis 180 than third weld 134 andfourth weld 186 is offset from fifth weld 184 along an axis,perpendicular to central axis 180 of bellows 108, and is closer tocentral axis 180 than fifth weld 184. The preceding subject matter ofthis paragraph characterizes example 45 of the present disclosure,wherein example 45 also includes the subject matter according to any oneof examples 29 to 44, above.

Second weld 138, being offset from third weld 134 along an axis,perpendicular to central axis 180 of bellows 108, and being closer tocentral axis 180 than third weld 134 helps to ensure first sensor 116remains communicatively coupled with interstitial space 126 by ensuringsecond weld 138 is clear of third weld 134 in radial direction relativeto central axis 180. Fourth weld 186, being offset from fifth weld 184along an axis, perpendicular to central axis 180 of bellows 108, andbeing closer to central axis 180 than fifth weld 184 helps to ensureinterstitial space 126 is open to second cavity 125 by ensuring fourthweld 186 is clear of fifth weld 184 in radial direction relative tocentral axis 180.

Referring generally to FIGS. 13B and 13C and particularly to, e.g.,FIGS. 2 and 3, according to method 200, first weld 136 is offset fromsecond weld 138 and third weld 134 along an axis, perpendicular tocentral axis 180 of bellows 108, and is further away from central axis180 than second weld 138 or third weld 134 and sixth weld 137 is offsetfrom fourth weld 186 and fifth weld 184 along an axis, perpendicular tocentral axis 180 of bellows 108, and is further away from central axis180 than fourth weld 186 or fifth weld 184. The preceding subject matterof this paragraph characterizes example 46 of the present disclosure,wherein example 46 also includes the subject matter according to any oneof examples 29 to 45, above.

First weld 136, being offset from second weld 138 and third weld 134along an axis, perpendicular to central axis 180 of bellows 108, andbeing further away from central axis 180 than second weld 138 or thirdweld 134 helps to ensure first sensor 116 remains communicativelycoupled with interstitial space 126 by ensuring first weld 136 is clearof second weld 138 and third weld 134 in radial direction relative tocentral axis 180. Sixth weld 137, being offset from fourth weld 186 andfifth weld 184 along an axis, perpendicular to central axis 180 ofbellows 108, and being further away from central axis 180 than fourthweld 186 or fifth weld 184 helps to ensure interstitial space 126 isopen to second cavity 125 by ensuring sixth weld 137 is clear of fourthweld 186 and fifth weld 184 in radial direction relative to central axis180.

Referring generally to FIGS. 13B and 13C and particularly to, e.g.,FIGS. 2 and 3, according to method 200, first weld 136 is offset fromsecond weld 138 and third weld 134 along central axis 180 of bellows 108and sixth weld 137 is offset from fourth weld 186 and fifth weld 184along central axis 180 of bellows 108. The preceding subject matter ofthis paragraph characterizes example 47 of the present disclosure,wherein example 47 also includes the subject matter according to any oneof examples 29 to 46, above.

First weld 136, being offset from second weld 138 and third weld 134along central axis 180 of bellows 108, helps to ensure first sensor 116remains communicatively coupled with interstitial space 126 by ensuringfirst weld 136 is clear of second weld 138 and third weld 134 in axialdirection along central axis 180. Sixth weld 137, being offset fromfourth weld 186 and fifth weld 184 along central axis 180 of bellows108, helps to ensure interstitial space 126 is open to second cavity 125by ensuring sixth weld 137 is clear of fourth weld 186 and fifth weld184 in axial direction along central axis 180.

Examples of the present disclosure may be described in the context ofaircraft manufacturing and service method 1100 as shown in FIG. 14 andaircraft 1102 as shown in FIG. 15. During pre-production, illustrativemethod 1100 may include specification and design (block 1104) ofaircraft 1102 and material procurement (block 1106). During production,component and subassembly manufacturing (block 1108) and systemintegration (block 1110) of aircraft 1102 may take place. Thereafter,aircraft 1102 may go through certification and delivery (block 1112) tobe placed in service (block 1114). While in service, aircraft 1102 maybe scheduled for routine maintenance and service (block 1116). Routinemaintenance and service may include modification, reconfiguration,refurbishment, etc. of one or more systems of aircraft 1102.

Each of the processes of illustrative method 1100 may be performed orcarried out by a system integrator, a third party, and/or an operator(e.g., a customer). For the purposes of this description, a systemintegrator may include, without limitation, any number of aircraftmanufacturers and major-system subcontractors; a third party mayinclude, without limitation, any number of vendors, subcontractors, andsuppliers; and an operator may be an airline, leasing company, militaryentity, service organization, and so on.

As shown in FIG. 15, aircraft 1102 produced by illustrative method 1100may include airframe 1118 with a plurality of high-level systems 1120and interior 1122. Examples of high-level systems 1120 include one ormore of propulsion system 1124, electrical system 1126, hydraulic system1128, and environmental system 1130. Any number of other systems may beincluded. Although an aerospace example is shown, the principlesdisclosed herein may be applied to other industries, such as theautomotive industry. Accordingly, in addition to aircraft 1102, theprinciples disclosed herein may apply to other vehicles, e.g., landvehicles, marine vehicles, space vehicles, etc.

Apparatus(es) and method(s) shown or described herein may be employedduring any one or more of the stages of the manufacturing and servicemethod 1100. For example, components or subassemblies corresponding tocomponent and subassembly manufacturing (block 1108) may be fabricatedor manufactured in a manner similar to components or subassembliesproduced while aircraft 1102 is in service (block 1114). Also, one ormore examples of the apparatus(es), method(s), or combination thereofmay be utilized during production stages 1108 and 1110, for example, bysubstantially expediting assembly of or reducing the cost of aircraft1102. Similarly, one or more examples of the apparatus or methodrealizations, or a combination thereof, may be utilized, for example andwithout limitation, while aircraft 1102 is in service (block 1114)and/or during maintenance and service (block 1116).

Different examples of the apparatus(es) and method(s) disclosed hereininclude a variety of components, features, and functionalities. Itshould be understood that the various examples of the apparatus(es) andmethod(s) disclosed herein may include any of the components, features,and functionalities of any of the other examples of the apparatus(es)and method(s) disclosed herein in any combination, and all of suchpossibilities are intended to be within the scope of the presentdisclosure.

Many modifications of examples set forth herein will come to mind to oneskilled in the art to which the present disclosure pertains having thebenefit of the teachings presented in the foregoing descriptions and theassociated drawings.

Therefore, it is to be understood that the present disclosure is not tobe limited to the specific examples illustrated and that modificationsand other examples are intended to be included within the scope of theappended claims. Moreover, although the foregoing description and theassociated drawings describe examples of the present disclosure in thecontext of certain illustrative combinations of elements and/orfunctions, it should be appreciated that different combinations ofelements and/or functions may be provided by alternative implementationswithout departing from the scope of the appended claims. Accordingly,parenthetical reference numerals in the appended claims are presentedfor illustrative purposes only and are not intended to limit the scopeof the claimed subject matter to the specific examples provided in thepresent disclosure.

What is claimed is:
 1. A method of fabricating a conduit, the methodcomprising steps of: attaching a first tubular-outboard-ply end of atubular outboard ply to a first inner collar portion of a first collarwith a third weld; attaching a second tubular-outboard-ply end of thetubular outboard ply, which is axially opposite the firsttubular-outboard-ply end of the tubular outboard ply, to a second innercollar portion of a second collar with a fifth weld; inserting a tubularinboard ply into the tubular outboard ply and advancing the tubularinboard ply along an interior of the tubular outboard ply until a firsttubular-inboard-ply end of the tubular inboard ply protrudes a firstdistance past the first inner collar portion, and a secondtubular-inboard-ply end protrudes a second distance past the secondinner collar portion, wherein the first distance is greater than a firstpredetermined distance, and the second distance is greater than a secondpredetermined distance; simultaneously corrugating the tubular inboardply and the tubular outboard ply to form a bellows, having a centralaxis and comprising a corrugated outboard ply, a corrugated inboard ply,and an interstitial space, interposed between the corrugated inboard plyand the corrugated outboard ply, wherein the corrugated outboard ply isformed from the tubular outboard ply, and the corrugated inboard ply isformed from the tubular inboard ply; trimming a firstcorrugated-inboard-ply end of the corrugated inboard ply, correspondingto the first tubular-inboard-ply end of the tubular inboard ply, tocreate a trimmed first corrugated-inboard-ply end that protrudes thefirst predetermined distance past the first inner collar portion;trimming a second corrugated-inboard-ply end of the corrugated inboardply, corresponding to the second tubular-inboard-ply end of the tubularinboard ply, to create a trimmed second corrugated-inboard-ply end thatprotrudes the second predetermined distance past the second inner collarportion; interconnecting the first inner collar portion and a firstouter collar portion of the first collar with a first weld;interconnecting the second inner collar portion and a second outercollar portion of the second collar with a sixth weld; attaching thetrimmed first corrugated-inboard-ply end of the corrugated inboard plyto the first outer collar portion with a second weld; attaching thetrimmed second corrugated-inboard-ply end of the corrugated inboard plyto the second outer collar portion with a fourth weld; andcommunicatively coupling a first sensor with the interstitial space. 2.The method according to claim 1, wherein the step of inserting thetubular inboard ply into the tubular outboard ply comprises insertingthe first tubular-inboard-ply end of the tubular inboard ply into thesecond tubular-outboard-ply end of the tubular outboard ply.
 3. Themethod according to claim 1, wherein, after the tubular inboard ply isadvanced along the interior of the tubular outboard ply, and after thetubular inboard ply and the tubular outboard ply are simultaneouslycorrugated, the first inner collar portion is interconnected with thefirst outer collar portion, and the second inner collar portion isinterconnected with the second outer collar portion.
 4. The methodaccording to claim 3, wherein the tubular inboard ply is inserted intothe tubular outboard ply after the first tubular-outboard-ply end of thetubular outboard ply is attached to the first inner collar portion, andafter the second tubular-outboard-ply end of the tubular outboard ply isattached to the second inner collar portion.
 5. The method according toclaim 4, wherein: the trimmed first corrugated-inboard-ply end of thecorrugated inboard ply is attached to the first outer collar portionafter the first inner collar portion and the first outer collar portionare interconnected with the first weld; and the trimmed secondcorrugated-inboard-ply end of the corrugated inboard ply is attached tothe second outer collar portion after the second inner collar portionand the second outer collar portion are interconnected with the sixthweld.
 6. The method according to claim 1, wherein: the first sensor iscommunicatively coupled with the interstitial space via a first channel,passing through one of the first inner collar portion or the first outercollar portion; and the first channel is cross-sectionallycircumferentially closed.
 7. The method according to claim 6, furthercomprising communicatively coupling a second sensor with theinterstitial space via a second channel, passing through one of thesecond inner collar portion or the second outer collar portion, whereinthe second channel is cross-sectionally circumferentially closed.
 8. Themethod according to claim 1, further comprising reducing pressure in theinterstitial space to below atmospheric pressure after the first sensoris communicatively coupled with the interstitial space.
 9. The methodaccording to claim 8, wherein the pressure in the interstitial space isreduced by creating a pressure gradient across a vacuum port,communicatively coupled with the interstitial space.
 10. The methodaccording to claim 9, further comprising sealing the vacuum port, afterthe pressure in the interstitial space is reduced, by closing apinch-off tube.
 11. The method according to claim 1, further comprising:flaring the first tubular-outboard-ply end of the tubular outboard plyto create a first flared portion of the first tubular-outboard-ply end,and wherein the step of attaching the first tubular-outboard-ply end ofthe tubular outboard ply to the first inner collar portion comprisesattaching the first flared portion of the first tubular-outboard-ply endto a first beveled weld-joint recess of the first inner collar portionwith the third weld; and flaring the second tubular-outboard-ply end ofthe tubular outboard ply to create a second flared portion of the secondtubular-outboard-ply end, wherein the step of attaching the secondtubular-outboard-ply end of the tubular outboard ply to the second innercollar portion comprises attaching the second flared portion of thesecond tubular-outboard-ply end to a second beveled weld-joint recess ofthe second inner collar portion with the fifth weld.
 12. The methodaccording to claim 1, further comprising: attaching a firstsecond-tubular-outboard-ply end of a second tubular outboard ply to thefirst inner collar portion with the third weld; attaching a secondsecond-tubular-outboard-ply end of the second tubular outboard ply,which is axially opposite the first second-tubular-outboard-ply end ofthe second tubular outboard ply, to the second inner collar portion ofthe second collar with the fifth weld; and corrugating the secondtubular outboard ply simultaneously with the tubular inboard ply and thetubular outboard ply to form the bellows, which further comprises asecond corrugated outboard ply; wherein: the tubular outboard ply isinterposed between the tubular inboard ply and the second tubularoutboard ply, and the second corrugated outboard ply is formed from thesecond tubular outboard ply.
 13. The method according to claim 1,wherein: the first outer collar portion of the first collar comprises afirst annular weld-joint recess; the second outer collar portion of thesecond collar comprises a second annular weld-joint recess; the trimmedfirst corrugated-inboard-ply end of the corrugated inboard ply isattached to the first annular weld-joint recess of the first outercollar portion by the second weld; and the trimmed secondcorrugated-inboard-ply end of the corrugated inboard ply is attached tothe second annular weld-joint recess of the second outer collar portionby the fourth weld.
 14. The method according to claim 1, wherein: afirst weld-joint groove is defined between the first outer collarportion and the first inner collar portion; a second weld-joint grooveis defined between the second outer collar portion and the second innercollar portion; the first inner collar portion is attached to the firstouter collar portion by filling the first weld-joint groove with thefirst weld; and the second inner collar portion is attached to thesecond outer collar portion by filling the second weld-joint groove withthe sixth weld.
 15. The method according to claim 1, further comprisingcoupling a sheath to the first inner collar portion of the first collarand to the second inner collar portion of the second collar before thefirst inner collar portion is interconnected with the first outer collarportion with the first weld and before the second inner collar portionis interconnected with the second outer collar portion with the sixthweld, wherein corrugated outboard ply is interposed between the sheathand the central axis of the bellows.
 16. The method according to claim1, wherein: the second weld is offset from the third weld along thecentral axis of the bellows; and the fourth weld is offset from thefifth weld along the central axis of the bellows.
 17. The methodaccording to claim 1, wherein: the second weld is offset from the thirdweld along an axis, perpendicular to the central axis of the bellows,and is closer to the central axis than the third weld; and the fourthweld is offset from the fifth weld along an axis, perpendicular to thecentral axis of the bellows, and is closer to the central axis than thefifth weld.
 18. The method according to claim 1, wherein: the first weldis offset from the second weld and the third weld along an axis,perpendicular to the central axis of the bellows, and is further awayfrom the central axis than the second weld or the third weld; and thesixth weld is offset from the fourth weld and the fifth weld along anaxis, perpendicular to the central axis of the bellows, and is furtheraway from the central axis than the fourth weld or the fifth weld. 19.The method according to claim 1, wherein: the first weld is offset fromthe second weld and the third weld along the central axis of thebellows; and the sixth weld is offset from the fourth weld and the fifthweld along the central axis of the bellows.
 20. The method according toclaim 2, wherein, after the tubular inboard ply is advanced along theinterior of the tubular outboard ply, and after the tubular inboard plyand the tubular outboard ply are simultaneously corrugated, the firstinner collar portion is interconnected with the first outer collarportion, and the second inner collar portion is interconnected with thesecond outer collar portion.